It is known that modern technique has supplied a large quantity of apparatuses based on the use of electric current; and this not only on a technical or industrial level, but also at any other level, as for schools, homes and so on.
Apart from a few cases of entirely sealed apparatuses, most of these apparatuses provide for no safe protection against electric current fulminations. In other words, there are many apparatuses having a structure such as to make it possible to create a contact--either directly or indirectly--between one part of the human body, particularly a hand of the user, and parts of the apparatus conducting electric current. In this case, the effects on the human body may either be very weak--as a simple electric shock--or most serious, as scalds or fulminations.
It should be noted in particular that, even if some electrically fed apparatuses have a structure such as not to allow a direct contact of the user's hand with electrically conductive parts, they however provide for no protection--nor is it on the other hand possible in certain cases--against an indirect contact, as may happen for example for the conduction produced by humidity or by water drops penetrating into the apparatus.
To make the above more clear, we can refer to a typical example of domestic apparatus being subject to the aforementioned drawbacks, and precisely to electric hair-driers, or to an equally typical example of industrial apparatus being subject to the same drawbacks, and precisely to cement mixers, particularly the small electrically fed mixers for building yards. It is obvious however that these examples have to be considered as purely indicative, since there are very many apparatuses involving the same problems.
For what concerns a hair-drier type apparatus, the danger derives from several circumstances:
--to start with, it is an apparatus which undergoes lots of movements during which the feeding cable is repeatedly bent in opposite directions and is hence subject, especially near the handgrip, to the breaking of the protection sheath: any uncovered wires in said position may easily cause electric discharges on the operator's hand, or short circuits; PA1 --even supposing that the wire is in perfect order, or that it is replaced as soon as it shows wear or ageing, the apparatus itself is of an essentially open type--just in relation to its function of heating and circulating air--and its openings lead directly onto electrically conductive parts, as the electric motor of the fan, or the electric heating element. Though excluding the possibility that the user might introduce a finger in such openings--which possibility should not really be excluded considering that such an apparatus may easily get into the hands of children--it is still certain that the steam present in a bath-room, or the humidity of the hands of those who have just washed their hair, or any water drops which might fall from the hair into the apparatus, are all elements which may lead to the conduction of electric current out of the apparatus itself, with consequent risks of fulminations. Nor can one fully exclude the possibility that an apparatus of this type may accidentally fall into the bath water while someone is having a bath, and in this case the risk of fulmination is even higher.
Substantially the same dangers occur, in the industrial field, when using an electric cement mixer. In this case, in fact, the motor for dragging the mixer is normally contained in a box which-- in order to allow a sufficient cooling of the motor itself--is provided with a number of openings. Though excluding, also in this case, that the operator might be so careless as to introduce some electrically conductive element, or even his fingers, into said openings, it is undoubted that--both when filling the mixer with cement and water, and when possibly washing the mixer with a water-spout--the danger that an electric current discharge may reach the operator, due to water conduction, should by no means be neglected.
A further danger derives moreover--in both the aforecited cases, as well as in all those cases in which the flexible feeding cable undergoes easy wear--from the fact that the insulation coating of said feeding cable may get peeled or torn, thus exposing the metallic conductive part of the cable itself. In this case, a direct contact--or even an indirect contact, for example through water conduction--of this exposed metal part, undoubtedly represents a risk of fulmination, as well as of short circuit.